There are no specific diets we recommend for prevention or treatment of any type of cancer (including mast cell tumors), or for pets undergoing cancer therapy. We do recommend that pets are fed a commercial, high-quality, well-balanced diet. If you would like to home-cook for your pet, we strongly recommend that a nutritionist is consulted to be sure that the diet contains adequate supplementation of vitamins and minerals. There are on-line resources such as balance-it.com to help with home-cooked diets. We also strongly advise against feeding raw food diets. Animals with cancer may have weakened immune systems, and will be more vulnerable to bacterial infections from raw or undercooked foods such as E. coli and salmonella. In addition, there are several reports of people becoming infected from their pets who contracted food-borne illness from contaminated foods. To my knowledge, there are no specific foods that will trigger a histamine reaction in dogs with mast cell tumors. Any dog with a mast cell tumor can have a histamine reaction (degranulation episode). Your veterinarian can give you information on what signs to watch for, and medication dosages of antihistamines such as Benadryl and Pepcid that might be helpful.